Sewers are pipes or conduits used to convey or direct various liquids, with or without entrained or suspended solids, from one point to another. There are generally two types of sewers: sanitary sewers and storm sewers. Sanitary sewers are used to convey sewage, waste water, and the like from a source (such as a house) to a suitable treatment facility. Storm sewers, on the other hand, are generally used to convey drainage or run-off water. In either case, it is generally desired to minimize the leakage of ground water into the sewer, be it of the sanitary- or storm-type. In the case of sanitary sewers, any such ground water leakage increases the volume of fluid that must be treated. In the case of storm sewers, such ground water leakage unnecessarily increases the volume of liquid carried by the sewer, and may exceed disposable or dispersal capabilities. Thus, it is generally desired to minimize the amount of ground water entering the sewer.
Sewers develop leaks for various reasons. Whatever the cause, such leaks permit ground water to enter the sewer. The ground water is generally pressurized positively relative to the pressure within the sewer, such that the ground water will flow naturally through any leakage path into the sewer.
The problem of repairing or sealing such leaks in sewers is complicated by the fact that such sewers are typically subterranean, and may be buried as deep as thirty feet beneath the surface. One technique, of course, is to dig up the entire sewer to expose the damaged portion. Another technique is to apply a grout or sealant from within the sewer to repair the damaged portion. However, such grout or sealant is typically applied to the inside of the sewer. Thus, its integrity is determined by the extent to which the grout or sealant adheres to the wall of the sewer. Many sewers are formed of a suitable plastic material, which further complicates the problem of adhering the grout or sealant thereto. Thus, there has long been a need to provide a device to allow the grout or sealant to pass through the sewer so as to bond to the outside thereof.
Additional details as to prior art sewer repair devices are shown in the following U.S. Pat. Nos. 3,834,422 (Larson), 3,915,197 (Piccirilli), 3,951,173 (Larson), 4,170,248 (Bennet et al.), 4,244,895 (Nakashin), 4,296,932 (Grobler), 4,529,008 (Appleton), 4,572,228 (Larson et al.), and 4,627,471 (Parkes et al.).